Scientists at the La Jolla Institute for Immunology have identified and characterized human antibodies that neutralize the measles virus by blocking its entry into the cell. This is the first time that antibodies have been shown to bind effectively to two essential viral proteins, creating a dual blockade that prevents infection. Unlike the current vaccine, which is based on an attenuated virus and is not recommended for immunocompromised individuals, these monoclonal antibodies could be used both as a new vaccine approach and as a treatment for the entire population.